1. Field of the Invention
The present invention relates to opening features for cartons and more particularly relates to line of weakness opening features.
2. Description of the Prior Art
Cartons have been designed to hold dry or liquid products. A typical carton has a core structural layer of paperboard providing the carton strength and rigidity. In a liquid type carton, a layer of aluminum foil is adhered to one surface of the paperboard and serves as a barrier layer against passage of contaminants into the carton. The inner surface and sometimes the outer surface is then coated with heat sealable plastic. While a number of specific constructions are known, it is generally accepted practice to provide such cartons with lines of weakness which facilitate the process of opening the carton for use of its contents.
Cut lines of weakness have been used as opening features. The cut lines of weakness are made by a knife blade mounting arrangement in a printing press which allows the carton blanks to be printed and cut at the same time. In such a process, the cut lines of weakness are cut all the way through the paperboard prior to the process of coating the paperboard with heat sealable plastic as described above. In such a manner, the paperboard is completely cut at the line of weakness while the plastic completely seals the package hermetically.
However, this method and apparatus have disadvantages and drawbacks. The expense in set-up and equipment for performing the simultaneous cutting and printing operation makes it prohibitive for smaller specialized production runs. In addition, this process for forming lines of weakness must be executed prior to the step of coating the paperboard with heat sealable plastic. This is because a knife cut which does not pass completely through the paperboard layer does not tear along the line of weakness whereas attempting to make a knife cut completely through the paperboard layer after the process of coating the paperboard with the plastic coating would greatly increase the chance of perforating the plastic coating and thus destroying the hermetic seal.
In addition, the current knife cut process, when used on the spout edge of a container for liquid material, tends to create an arrangement on the spout edge which allows liquid poured from the spout to dribble down the outside of the container during or after pouring.
Therefore, it is an object of the present invention to provide a carton having a line of weakness opening feature which can be readily manufactured in any quantity in a cost effective manner.
It is a further object of the invention to provide a carton having a line of weakness which can be formed subsequent to printing and coating with a heat sealable plastic.
It is an additional object of the invention to provide a carton with its pour spout that can be readily manufactured in any bulk quantity.
It is still a further object of the present invention to provide a carton having a pour spout opened by tearing along a line of weakness that forms an edge on the spout that resists dribbling of the liquid poured from the spout.
It is an additional object of the present invention to provide a carton having a line of weakness which provides for ease in opening and hermetic sealing which avoids the need for a separate inner liner to hold the carton contents.
It is still an additional object of the present invention to provide a carton having a line of weakness which provides for ease in opening and accuracy in tearing along the line of weakness.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.